WO2003027337A1

WO2003027337A1 - Improved angular channel processing

Info

Publication number: WO2003027337A1
Application number: PCT/AU2002/001303
Authority: WO
Inventors: Gabriel Stecher; Peter Thomson
Original assignee: Monash University
Priority date: 2001-09-24
Filing date: 2002-09-23
Publication date: 2003-04-03
Also published as: AUPR788801A0

Abstract

An angular channel processing machine (10) including a die (12) which defines first and second channels (13,15) that intersect at an angle, drive means (11) to drive a workpiece (23) through the first channel (13) in a direction toward the second channel (15). The second channel (15) is defined by a die surface (22) and an outer cylindrical surface (21) of a second channel rotatable roll (14) which are disposed in facing relationship. The angular arrangement of the first and second channels (13,15) is such that the workpiece (23) undergoes shear deformation at the region of intersection between the first and second channels (13,15) through engagement with the outer cylindrical roll surface (21).

Description

IMPROVED ANGULAR CHANNEL PROCESSING

The present invention relates to a machine and a method for processing metals in an improved manner by angular channel processing in which a metal is passed through a die having a pair of channels disposed at an angle to each other. The present invention is in particular, although not exclusively, concerned with a machine and method for equal channel angular processing in which the channels have substantially equal cross-sections, although it is to be appreciated that the invention is not limited to equal cross-sectional channels and includes channels of non-equal cross-sections. It will nevertheless be convenient to describe the invention in relation to the form of the invention which displays channels of substantially equal cross-section.

Equal channel angular processing ("ecap") is a form of metal processing by shear deformation. Ecap is the subject of academic publications and the present invention is directed to a new method and machine for performing ecap in an improved manner, rather than to the principles of ecap itself. Ecap involves subjecting a metal workpiece to simple shear deformation without reduction, or at least without significant reduction, through the cross-sectional area of the workpiece. The process of deformation by simple shear is distinct from deformation by bending. Deformation by shear is achieved by forcing the workpiece through a die which consists of two channels of equal channel section that intersect at an angle normally between 90° and 135°, but not limited to that angular range, hence equal channel angular processing. By this mechanism, the workpiece undergoes plastic deformation by shear instead of deformation by bending and this permits the workpiece to be deformed to very high strains, advantageously facilitating changes in the mechanical properties of the workpiece, such as in grain size and crystallographic texture. This can provide for substantial improvement in the formability of the workpiece. Ecap may also be employed for breaking up cast structures and for workpiece densification. As a particular advantage, ecap beneficially permits large, uniform, unidirectional deformations under relatively low pressure and load. Further advantages will become clear from the discussion which follows.

Ecap has been approached previously, generally as either an extrusion or a drawing process, but neither approach has met with any significant commercial application and ecap therefore remains largely ignored by industry despite the perceived benefits. As an extrusion process, a punch or ram has been employed to feed a workpiece into an ecap die comprising two intersecting channels. In a different ecap extrusion process employed in the applicants' understanding, experimentally only, a workpiece in the form of elongated feedstock, has been introduced into a grooved wheel and rotation of the wheel feeds the workpiece into an ecap die. In this later process, the friction between the feedstock and the wheel is required to be sufficient to drive the workpiece through the die. In the alternative drawing process, a preformed workpiece has been gripped by a suitable drawing mechanism and drawn through an ecap die. In a further alternative process, the first or entry channel of the die is defined on one side or face by a movable plate, which is movable in a direction toward the second channel to drag the workpiece through the die.

Each of the above extrusion and drawing processes involve significant drawbacks. The ecap extrusion process has been found to be susceptible to buckling of the extrusion ram or punch, and because of that, the process is limited in the length of feedstock it can handle. It therefore is limited to batch processing. On the other hand, ecap drawing is not so limited but the drawing method, along with each of the above extrusion methods, cannot effectively process metal sheet, but instead are limited to bar or wire feedstock. Also, the mechanism of deformation promoted by ecap is inherently unstable under tension and a uniform cross-section is not produced unless a heavy forward pressure is applied simultaneously behind the material entering the channel. The limitation of a grooved wheel to feed equal channel angular extrusion is a result of dependence on the sides of the groove to provide a net force to advance the workpiece into the die, because the friction force on the top and bottom surfaces of the workpiece are in opposite directions and therefore cancel each other approximately.

It is an object of the present invention to provide an improved method and machine for angular channel processing and in particular, for equal channel angular processing. It is a further object of the invention to provide a method and a machine which facilitates improved processing of metal sheet.

According to the present invention there is provided a machine including a die which defines first and second channels that intersect at an angle, drive means to drive said workpiece through said first channel in a direction toward said second channel, said second channel being defined by a die surface and an outer cylindrical surface of a second channel rotatable roll which are disposed in facing relationship, the angular arrangement of said first and second channels being such that said workpiece undergoes shear deformation at the region of intersection between said first and second channels through engagement with said outer cylindrical roll surface.

A method for processing metals, including feeding a workpiece to be treated into a first channel of a die and driving said workpiece through said first channel by drive means, said workpiece being driven to enter a second channel which intersects with said first channel and which is disposed at an angle to said first channel, said second channel being defined by a die surface and an outer cylindrical surface of a second channel rotatable roll which are disposed in facing relationship, said workpiece undergoing shear deformation at the region of intersection between said first and second channels through engagement with said outer cylindrical roll surface.

In each of the machine and method of the invention, it is preferred that the first and second channels have substantially equal cross-sections at the regions of their intersection and that the workpiece undergoes shear deformation substantially without any reduction in cross-section. However, the invention can be arranged for control of output thickness so that the output is either thicker or thinner than the input. This can permit the invention to provide accurate output thickness of a wide thickness range, even though the input material may be sourced from a limited feed stock inventory. From a commercial point of view, this may be a significant benefit provided by the invention.

The drive means of the invention preferably takes the form of drive rolls, which may engage the workpiece on one side only, but preferably which engages the workpiece on the opposite faces thereof. The drive means could however take other forms, such as continuous drive bands or belts.

The invention provides a variety of advantages compared with the prior art, in particular with prior art ecap. Whereas ecap by extrusion which employs a punch or ram is a batch process, the invention can produce a continuous, uniform product limited only by the length of the feed metal. Thus, the product of the invention is not required to undergo complicated joining processes associated with the batch extrusion method. Moreover, the invention is suitable for use with a workpiece having a wide, thin cross-section and therefore is particularly and highly advantageously suitable for processing metal sheet. However, the invention could be applicable to workpieces of other cross- section. The use of drive rolls also facilitates a reduction in the frictional forces to which workpieces have previously been exposed in prior art machinery and that results in reduced tool wear. The invention further can eliminate the formation of flash which is sometimes formed in the prior art extrusion methods, and which occurs when the workpiece forces a passage between the die and the feed mechanism or between parts of the die.

Each channel of the invention may be of any desired cross-section and the outer cylindrical roll surface has a profile complementary to the cross- section. The first channel of the invention preferably is of substantially uniform cross-section throughout its length, defined by a pair of generally planar surfaces, which are spaced apart and parallel. Advantageously, the surfaces may be spaced close together and have a significant width compared to the spacing, to facilitate processing of thin metal sheet. The spacing between the planar surfaces may be adjustable to accommodate workpieces of different thicknesses. Alternatively, the planar surfaces may be disposed at an angle to each other, so as to converge towards the intersection with the second channel while the angle of convergence may also be adjustable. The first channel may extend for any suitable length and may be of any suitable width. The width may be arranged to accommodate a range of workpieces of different width and means may be provided so that the machine can properly process a workpiece which is of a lesser width than the first channel. Spacing means may be provided for example on either or each side of a workpiece of lesser relative width, to ensure the workpiece travels through the first channel properly and is prevented from sideways motion. Such spacing means may be employed through the second channel also and downstream of the second channel.

The second channel roll can be disposed at any suitable angle to the first channel, although preferably the angle is in the region of or between 90° and 135°. The selected intersection angle can relate to the material being processed and the characteristics required by the processing. In one form of the invention, the apparatus permits adjustability of the intersection angle. This enables the most appropriate angle to be chosen for the characteristics required and the material being processed.

The second channel roll can be freely rotatable such that friction between the workpiece and the cylindrical outer surface during workpiece travel past the second channel roll causes the roll to rotate. Alternatively, the roll may be driven at a lesser or greater speed than the workpiece as may be required to assist with deformation of the workpiece through the die. A lesser speed would have the effect to increase hydrostatic compression during workpiece deformation at the channel intersection, to resist cracking of the workpiece. Still alternatively the roll can be arranged to rotate in the opposite or reverse direction to the direction of workpiece flow through the second channel. Driving the second channel roll in the reverse direction might be appropriate to compress the metal at the junction between the first and second channels, in order to close cracks that propagate in less ductile materials. The same general effect, but to a lesser extent, might occur if second channel roll was driven in the same direction but at a lesser speed, than the workpiece, whereas driving the roll in the same direction and faster than the workpiece will help to pull the workpiece through the die. This latter arrangement will also decrease the required pushing force in the first channel. The direction of rotation depends on the characteristics required by ecap.

The die surface of the second channel preferably is planar and preferably depends from an end of one of the planar surfaces of the first channel. In this arrangement, the outer cylindrical surface of the second channel roll is disposed adjacent the end of the other of the planar surfaces of the first channel, and the proximity of the outer cylindrical surface to the end of that planar surface is such as to prevent the workpiece from a path other than through the second channel. That is, the outer cylindrical surface may be spaced from the end of the relevant planar surface, but the spacing must not be sufficient for the workpiece to take a different path other than through the second channel. The proximity of the outer cylindrical surface to the end of the respective planar surface is also such as to define a cross-section of substantially equal dimensions to the first channel.

In the arrangement in which the die surface of the second channel is a planar surface, the cross-section of the second channel in the direction of travel of the workpiece will vary, given the curved nature of the cylindrical outer surface. However, the greater the radius of the second channel roll, the less the cross-sectional variation will be. Advantageously, the length of the second channel can be quite short, as the major deformation of the workpiece generally will occur at the intersection of the first and second channels and extended engagement of the workpiece with the second channel, effectively further constraint of the workpiece, may lead to counterproductive wear of the machine. Accordingly, the workpiece can exit the second channel very soon, and typically almost immediately beyond the intersection of that channel with the first channel.

In an alternative arrangement, the die surface of the second channel is curved complementary to and spaced from the outer cylindrical surface of the second channel roll to define a concave second channel. Drive means are disposed at the exit of the second channel to engage and drive the workpiece and this arrangement permits the application of a controlled tension or compression to the workpiece. The second channel can have any desirable curved extent, such as in the region of 10° to 90° of the extent of the outer cylindrical surface, although an extent of about 70° is preferable.

Drive rolls are the preferred drive means, and these may comprise a single pair of rolls only, or a plurality of pairs may be provided, preferably lengthwise of the first channel. Each of the drive rolls preferably are pinch rolls.

The number of drive rolls in one aspect, is determined by the compressive stress which the rolls are required to impose on the workpiece at the intersection between the first and second channels. An array of five pairs of drive rolls may for example, be provided, so that the compressive load applied to the workpiece progressively increases toward the point of intersection of the first and second channels. The drive rolls may extend in full contact with the workpiece across the width of the first channel, or the rolls may be of reduced width so as to engage the workpiece at a single location, or at two or more locations spaced across the width. By having no limitations on the number of drive roll pairs, the process of the machine is adjustable or scalable both in respect of workpiece properties and dimensions, which can realise a benefit not available in prior ecap processes. The drive rolls extend a suitable distance into the first channel in order engage the opposite faces of the workpiece and the extent of the rolls into the first channel may be adjustable to accommodate workpieces of different thickness. This may be separate from, or in conjunction with spacing adjustment of the planar surfaces of the first channel. Each pair of rolls may be arranged to extend into the first channel the same amount, or a different amount, depending on the required treatment of the workpiece. For example, the rolls may extend further into the first channel progressively toward the intersection with the second channel. The rolls apply a compressive load to the workpiece, both in the direction of workflow and normal to the workflow. In the preferred arrangement, the load applied normal to the workflow is within the elastic range, so that the workpiece is not permanently deformed as it passes through the drive rolls.

The invention can include drawing means for applying a tensile load to the workpiece to assist workpiece travel through the first and second channels. The invention can also include compression means for applying compression to the workpiece. Each of the drawing means and the compression means preferably is applied to the workpiece downstream of the second channel and each may be embodied in a single facility that achieves both of the drawing and compression functions. Such a facility may take the form of one or more stands of a rolling mill comprising pairs of rolls disposed in facing relationship on opposite sides of the workpiece and arranged for engagement with each of the opposite sides. Each of the rolls can be driven in the direction of motion of the workpiece to apply a tensile load. The invention can include provision for other treatment, of the workpiece, such as heat treatment, and the invention embodies treatment of a workpiece through a plurality of ecap stages. For this, two or more ecap machines may treat a workpiece in series, to achieve particular characteristics or a single machine may embody more than one ecap stage. The ecap stages may differ in the treatment of the workpiece, such as in the angle at which the first and second channels intersect and the compressive or tensile load imposed on the workpiece. Treatments such as the aforementioned heat treatment may take place between or within successive ecap stages. In one arrangement, heating means may be applied between the drive rolls of the first channel and the second channel roll, to heat the workpiece close to the region of shear deformation at the intersection of the first and second channels. The heating means preferably heats the opposed faces of the first channel, although any suitable heating arrangement may be employed. In the arrangement in which a plurality of drive roll pairs are provided in the direction of workpiece flow, the heating means preferably is applied downstream of the drive roll pair which is closest to the intersection of the first and second channels. Alternatively, in the arrangement in which the drive means takes the form of a continuous band or belt, the band or belt may be heated. The heat applied to the workpiece can be sufficiently high to heat treat it and to lower the load required to deform it by shear.

The invention facilitates processing of metal, in particular metal sheet, by shear deformation, to refine the grain size by rotational recrystallisation, or, more usually, by interposing a stage of process annealing for static recrystallisation. Put differently, the invention applies a plastic work to the metal followed by recrystallisation, which is envisaged to improve the properties of the metal with respect to press formability. Particularly in respect of aluminium sheet, shear deformation is envisaged to enhance formability. Accordingly, the invention potentially could become a processing step in virtually all ferrous and non-ferrous sheet used in press forming, such as the production of panels for the whitegoods, the automotive and the aeronautical and aerospace industries. The invention could also open the way for greater use of magnesium alloys, by refining the grain size of such alloys and thereby substantially improving overall ductility. The invention is considered to have the potential to induce superplasticity by thermo mechanical processing without depending on adjustment of the chemistry of the metal. The invention could therefore elevate superplastic forming to the preferred technique for many components of complex shape. The attached drawings show an example embodiment of the invention of the foregoing kind. The particularity of those drawings and the associated description does not supersede the generality of the preceding broad description of the invention. Figure 1 is a schematic view of a machine according to one embodiment of the invention.

Figure 2 is an enlarged view of one section of the apparatus of Figure 1. Figure 3 is a schematic view of a machine according to a second embodiment of the invention.

The machine 10 of Figure 1 includes a plurality of drive rolls 11, arranged in facing pairs, lengthwise of a die section 12 which defines a first channel 13. Five pairs of drive rolls 11 are shown, although a lesser or greater number can be provided as necessary. Each roll 11 of each pair of drive rolls is driven to rotate in opposite directions so as to impart a driving force on a workpiece disposed within the first channel and to drive the workpiece through the first channel. The means employed to drive the drive rolls 11 can be of any suitable form and in one arrangement will include an electric motor drive which drives a main gear wheel, which is in meshed engagement with a plurality of secondary gear wheels, each of which is formed about the shaft of a drive roll 11. Other mechanisms may also be suitable for driving the drive rolls 11.

The machine 10 further includes a second roll 14, which in part defines a second channel 15. This arrangement is more clearly shown in Figure 2 and reference will now be made to that figure. Figure 2 shows the first channel 13 and the second channel 15 in more detail. It can be seen that the first channel 13 is defined by a pair of facing planar surfaces 16 and 17, which form the internal surfaces of a pair of opposed die parts 18 and 19. The separation between the planar surfaces 16 and 17 is constant so that the cross-section of the first channel 13 lengthwise in the direction of workpiece travel is uniform. The width of the planar surfaces 16 and 17 can be of any suitable width.

Figure 2 further shows a single pair of drive rolls 11 in facing relationship and disposed on either side of the first channel 13. The direction of rotation of the rolls 11 is shown by the arrows A and from these it can be seen that rolls 11 rotate in opposite directions. The rolls 11 are accommodated in the die parts 18 and 19, so as to project slightly into the first channel 13 and by that projection, the rolls can engage against opposite sides of a workpiece within the first channel to drive the workpiece through that channel. The arrangement shown in Figure 2 shows each of the rolls 11 accommodated within circular arcs 20 in the respective die parts 18 and 19, which recesses open into the first channel 13 to permit the rolls 11 to extend into that channel. The other pairs of drive rolls 11 shown in Figure 1 are likewise accommodated in similar recesses.

The second channel 15 is shown in Figure 2 as extending at 90° to the first channel 13, although it could extend at an alternative angle. For example, it could approach 180° or it could be less than 90°, but the preferred range is between 90° and 135°. The second channel 15 is defined by the cylindrical outer surface 21 of the second channel roll 14 and the facing die surface 22. The die surface 22 is planar although it could be concave or convex and is formed as part of the die part 19 extending perpendicular to the planar surface 17. The first and second channels intersect in the region of the junction between the die surfaces 17 and 22. The planar surface 16 extends into very close proximity with the outer surface 21 of the roll 14 so as to substantially eliminate any gap between those surfaces and to promote workpiece travel exclusively through the second channel 15. A workpiece 23 is shown in Figure 2, egressing from the second channel 15. The workpiece 23 is of the same. or at least substantially the same cross-sectional thickness T when it egresses from the second channel 15 as compared to when it enters the first channel 13. The workpiece 23 has therefore been subjected only to a plastic deformation at the intersection of the first and second channels without a reduction in cross- sectional area. It will be appreciated from Figure 2, that the second channel 15, as defined by the curved surface 21 and the planar surface 22, has a non- uniform cross-section in the direction of workpiece travel. That non-uniformity is only slight, given the large radius of the roll 14 compared with the thickness T of the workpiece.

It can further be appreciated from Figure 2, that the lengthwise extent of the second channel 15 is short relative to the lengthwise extent of the first channel 13. This is appropriate, given that the deformation to which the workpiece 23 is subjected occurs in the main at the junction between the first and second channels 13 and 15 and, subject to controlling the path of the workpiece after deformation, it is appropriate for the workpiece to exit the second channel soon after deformation.

The second channel roll 14 is preferably adjustable in one or each of two directions. Preferably it is adjustable vertically and/or in the direction of workpiece travel through the second channel. This latter movement allows an operator to ensure that the workpiece engages the second channel roll 14 slightly ahead of its axis, which promotes travel of the workpiece through the second channel in the desired direction and not in the reverse direction. The operation of the machine 10 is as follows. A workpiece 23 is fed into the die part 12 and is engaged by the array of drive rolls 11, which drive the workpiece 23 toward the second channel roll 14. The workpiece 23 experiences a progressively increasing compression through the array of drive rolls 11 as it proceeds through the array. At any suitable point, such as at the entry to the channel 13, or at the region following the last pair of drive rolls 11, before the intersection with the second channel 15, heating means may be employed to heat the workpiece. At the intersection of the first channel 13 with the second channel 15, the direction of workpiece travel changes abruptly through 90° and the workpiece is pushed through the change in direction by the drive rolls 11. The second channel roll 14 is rotatable in the direction of workpiece travel as shown and it may be free to rotate or it maybe driven to rotate at any suitable speed. The rotation of the roll 14 in the direction shown can eliminate tangential frictional force between the radial outer surface 21 and the workpiece 23 by driving the roll 14 at the same forward component of speed as the workpiece travel The roll 14 may instead be driven faster than the forward component of speed of the workpiece to assist travel of the workpiece into the die and to thereby reduce the drive force the drive rolls are required to exert on the workpiece. Alternatively, the workpiece may be compressed during shear if the roll 14 is driven at a lower speed than that of the workpiece travel. A retarded roll rotation may assist to suppress fracture of the workpiece. The roll 14 can instead bβ driven in the reverse direction to that shown in Figure 1.

Referring to Figure 1, the workpiece 23 egressing from the second channel 15 is engaged by a rolling mill 24. The rolling mill 24 as shown, consists of a pair of back-up rolls 25 and a pair of work rolls 26 with the work rolls 26 in engagement with opposite surfaces of the workpiece 23. The rolling mill 24 applies a controlled tension to the workpiece 23 egressing from the second channel 15 and it also can apply a compressive load normal to the workpiece travel, to further treat the workpiece, to improve dimensional accuracy and surface finish, to guide the workpiece and reduce the load required to drive the workpiece into the first and second channels. A lateral constraint may be applied to the workpiece to prevent buckling under a compressive load. For example, the workpiece may be constrained in a channel or the like when the compressive load is applied. The machine 10 advantageously achieves the benefits of ecap, but in an improved and commercially viable manner compared to the prior art. To enhance the ecap process, the machine 10 can include further treatment facilities and can for example, include heat treatment. Moreover, a workpiece may be treated in succession through two or more of the machines 10 which may be aligned in series, possibly with other treatments, such as heat treatment, taking place between one or more of the machines

Figure 3 shows an alternative machine to Figures 1 and 2 although it retains many of the features of those figures. Accordingly, like parts in the machine of Figure 3 have the same reference numeral, plus 100. In the Figure 3 machine 40, the die part 112 includes die parts 118 and 119 and drive roll 111. These function in the same manner as the like parts of Figures 1 and 2, so that the die parts 118 and 119 define a first channel 113 into which is fed a workpiece 123 (shown exiting the machine 40).

The machine 40 includes a second roll 114, which in part defines a second channel 41. The second channel 41 is further defined by a second channel die part 42, which can be formed integrally or separately with the first channel die part 119. As can be-seen from Figure 3, the second channel 41 defines a concave channel path, although at the junction between the first and second channels, the workpiece will experience the same 90° change in direction as that which occurs in the Figures 1 and 2 arrangement.

The second channel can have any suitable circumferential or arc extent and can therefore be equal to, or more or less than that shown in Figure 3. For example, the extent can be in the region of 10 ° to 90 °, but preferably about 70°. A pinch roll 43 engages the workpiece 123 at the exit of the second channel 41. The Figure 3 machine advantageously facilitates the application of controlled tension or compression to the workpiece 123. This is achieved by advancing or retarding the torque on the second channel roll 114 and the pinch roll 43 the amount required, relative to the drive load imparted on the workpiece by the drive rolls 111. Moreover, because the workpiece in constrained in the second channel 41 as shown, the application of a compressive load will not result in the workpiece buckling.

The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the spirit and scope of the above description.

Claims

1. An angular channel processing machine including a die which defines first and second channels that intersect at an angle, drive means to drive a workpiece through said first channel in a direction toward said second channel, said second channel being defined by a die surface and an outer cylindrical surface of a second channel rotatable roll which are disposed in facing relationship, the angular arrangement of said first and second channels being such that said workpiece undergoes shear deformation at the region of intersection between said first and second channels through engagement with said outer cylindrical roll surface.

2. A machine according to claim 1 , said first and second channels having substantially equal cross-sections at the region of their intersection, and said workpiece undergoing said shear deformation substantially without any reduction in cross-section.

3. A machine according to claim 1 or 2, said drive means including drive rolls, engaging said workpiece on at least one side thereof.

4. A machine according to claim 3, said drive rolls being disposed in facing relationship on opposite sides of said first channel and being arranged for engagement in use, with opposite faces of a workpiece disposed within said first channel.

5. A machine according to claim 1, said drive means including continuous drive belts or bands.

6. A machine according to any one of claims 1 to 5, said first channel being defined by a pair of opposed generally planar surfaces which are spaced apart and parallel.

7. A machine according to claim 6, said generally planar surfaces being spaced close together and having significant width for processing a workpiece of thin metal sheet.

8. A machine according to claims 6 or 7, the spacing between said generally planar surfaces being adjustable.

9. A machine according to claim 6, said generally planar surfaces being disposed at an angle to each other, to converge towards said intersection with said second channel.

10. A machine according to claim 9, said angular disposition between said planar surfaces being adjustable.

11. A machine according to any one of claims 1 to 10, spacing means being provided in said first channel to guide a workpiece through said first channel when the width of said workpiece is less than the width of said first channel.

12. A machine according to claim 11 , said spacing means being provided on each side of said first channel.

13. A machine according to claim 11 or 12, said spacing means being provided also in said second channel.

14. A machine according to any one of claims 1 to 13, said first and second channels being disposed at an angle to each other in the region of or between 90° to 135°.

15. A machine according to any one of claims 1 to 14, said angle of disposition between said first and second channels being adjustable.

16. A machine according to any one of claims 1 to 15, said second channel roll being freely rotatable and being rotated by workpiece travel through said die.

17. A machine according to any one of claims 1 to 16, said second channel roll being drivable by drive means to rotate between the range of less than to greater than the speed of the workpiece through the die.

18. A machine according to any one claims 1 to 15, said second channel roll being drivable in the reverse direction to the direction it would rotate if it was driven by workpiece travel through the die.

19. A machine according to any one of claims 1 to 18, said second channel die surface being planar.

20. A machine according to any one of claims 1 to 18, said second channel die surface being concave curved complementary to and spaced from but adjacent to said outer cylindrical surface of said second channel roll, said second channel thereby having a curved extent, and a second channel drive means being disposed at the exit end of said second channel to engage and drive said workpiece.

21. A machine according to claim 20 said drive means being a pinch roll.

22. A machine according to claim 20 or 21 , said second channel roll and said second channel drive means being rotatable to apply a tensile or compressive load to the workpiece.

23. A machine according to any one of claims 20 to 22, said second channel having an arc length in the region of or between 10° to 90°.

24. A machine according to claim 6, said second channel die surface depending from an end of one of said pair of planar surfaces of said first channel.

25. A machine according to claim 24, said outer cylindrical surface of said second channel roll being disposed adjacent to an end of the other of said pair of planar surfaces of said first channel, the adjacent proximity of said outer cylindrical surface to said planar surface end being so proximate as to prevent travel of said workpiece from a path other than through said second channel.

26. A machine according to any one of claims 1 to 25, said drive rolls comprising a pair of drive rolls, or a plurality of pairs of drive rolls.

27. A machine according to claim 26, said pairs of drive rolls of said plurality of pairs of drive rolls being spaced lengthwise of said first channel.

28. A machine according to any one of claims 1 to 27, said drive rolls being pinch rolls.

29. A machine according to any one of claims 1 to 28, said drive rolls applying a compressive stress to said workpiece.

30. A machine according to claim 29, said drive rolls applying a compressive stress to said workpiece that progressively increases toward said intersection between said first and second channels.

31. A machine according to any one of claims 1 to 30, said drive rolls engaging said workpiece across the full width of said workpiece.

32. A machine according to any one of claims 1 to 30, said drive rolls engaging said workpiece at a single location, or at two or more separate locations across the width of said workpiece.

33. A machine according to any one claims 1 to 32, the extent to which said drive rolls extend into said first channel being adjustable.

34. A machine according to any one of claims 1 to 33, further including drawing means for applying a tensile load to said workpiece to assist workpiece travel through said first and second channels.

35. A machine according to any one of claims 1 to 34, further including compression means for applying compression to said workpiece.

36. A machine according to any one of claims 1 to 33, including drawing means for applying a tensile load to said workpiece to assist workpiece travel through said first and second channels and compression means for applying compression to said workpiece, each of said drawing means and said compression means being applied to said workpiece downstream of or within said second channel.

37. A machine according to claim 36, said drawing means and said compression means being embodied in a single facility, said facility taking the form of one or more stands of a rolling mill which includes pairs of rolls disposed in facing relationship on opposite sides of said workpiece and arranged for engagement with said opposite sides, and said rolls being drivable in or against the direction of workpiece travel to respectively apply tensile or compressive load.

38. A machine according to any one of claims 1 to 37, further including heating means for heating said workpiece.

39. A machine according to claim 3 or 4, heating means being applied between said drive rolls of said first channel and said second channel roll, or to one or more of said drive rolls and/or said second channel roll. .

40. A machine according to claim 5, said belts or bands being heated to heat said workpiece.

41. A machine according to claim 6, further including heating means for heating said planar surfaces of said first channel.

42. A machine according to claim 6, said planar surfaces being formed on opposing faces of a pair of die parts and said die parts including one or more recesses to each accommodate at least partly, a drive roll, said recesses opening into said first channel to permit said drive rolls to extend into said first channel and engage and drive a workpiece disposed within said first channel.

43. A machine according to any one of claims 1 to 42, said second channel roll being adjustable in a direction to increase the width of said second channel and/or in the direction of workpiece travel through said second channel.

44. A machine according to claim 25, said second channel roll being positioned so that said workpiece engages said outer cylindrical surface thereof ahead of, in the direction of workpiece travel, the axis of rotation of said second channel roll.

45. A method for processing metals, including feeding a workpiece to be treated into a first channel of a die and driving said workpiece through said first channel by drive means, said workpiece being driven to enter a second channel which intersects with said first channel and which is disposed at an angle to said first channel, said second channel being defined by a die surface and an outer cylindrical surface of a second channel rotatable roll which are disposed in facing relationship, said workpiece undergoing shear deformation at the region of intersection between said first and second channels through engagement with said outer cylindrical roll surface.

46. A method according to claim 45 said first and second channels having substantially equal cross-section at the region of their intersection, and said workpiece undergoing said shear deformation substantially without any reduction in cross-section.

47. A method according to claim 45 or 46, said angle of intersection between said first and second channels being in the region of or between 90° to 135°-

48. A method according to any one of claims 45 to 47, said second channel roll freely rotating through engagement with said workpiece as said workpiece travels through said die.

49. A method according to any one of claims 45 to 47, said second channel roll being driven to rotate between the range of less than to greater than the speed of the workpiece through the die.

50. A method according to any one of claims 45 to 47, said second channel roll being driven in the reverse direction to the direction it would rotate if it was driven by workpiece travel through the die.

51. A method according to any one of claims 45 to 50, said drive means applying a compressive stress to said workpiece.

52. A method according to claim 51 , said compressive stress applied to said workpiece progressively increasing toward said intersection between said first and second channels.

53. A method according to any one of claims 45 to 52, further including drawing means for applying a tensile load to said workpiece to assist workpiece travel through said first and second channels and compression means for applying compression to said workpiece.

54. A method according to any one of claims 45 to 53, further including heating said workpiece prior to said intersection between said first and second channels.